Means and method for vapor and fog generation



E. F. ANDREWS 3,037,939

MEANS AND METHOD FOR VAPOR AND FOG GENERATION June 5, 1962 7 Sheets-Sheet 1 Filed July 3. 1956 N% NN m NQ DD DN June 5,. 1962 E. F. ANDREWS 3,037,939

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June 5, 1962 E. F. ANDREWS MEANS AND METHOD FOR VAPOR AND FOG GENERATION 7 Sheets-Sheet 6 Filed July 3, 1956 June 5, 1962 E. F. ANDREWS MEANS AND METHOD FOR VAPOR AND FOG GENERATION Filed July 3, 1956 7 Sheets-Sheet '7 lllll 90/:0'21/12757/ v Md firlzar-em 3,037,939 Patented June 5, 1962 3,037,939 MEANS AND METHOD FDR VAPGR AND FUG GENERATIGN Edward F. Andrews, Belleair Beach, Fla. (208 S. La Salle St., Chicago 4, HI.) Filed July 3, 1956, Ser. No. 595,738 23 Claims. (Cl. 252-305) My invention relates to means and a method for vapor generation and for producing a thermal aerosol or fog for purposes .of concealment, for controlling atmospheric temperature, for disseminating insecticide or other materials into the outside atmosphere or confined spaces, etc. My co-pending patent application Serial No. 303,137 filed August 7, 1952, now Patent No. 2,765,578, contains similar subject matter. I Apparatus covered by my invention is well adapted to producing heated vapor under pressure by means requiring little or no mechanical power which is of particular advantage in connection with portable applications.

It is an object of my invention to provide means and a method for vapor and/or aerosol generation requiring little or no mechanical power which is simple and economical and otherwise advantageous.

It is a more specific object to generate a fog or aerosol with light, highly portable apparatus which is well adapted to be made in small manually portable form as well as in large units of higher output.

It is a further object to generate a thermal aerosol in such a way as to minimize the exposure of heat-sensitive material to excessive temperature and to reduce the time of exposure thereto.

Other objects and advantages of my invention will be made apparent in the following drawings and description of operation.

My invention may take the form of a double-Walled duct through which a flow of hot gases is established by means later to be described. Fuel under pressure from its own evaportion or pressurized by other means is supplied to a burner. water, oil, etc., is vaporized in a boiler inside the duct. The vapor under pressure issues from a jet nozzle connected to the boiler and may augment and mix with the flow of hot gases from said duct to form a fog jet with or Without insecticide or other material. The insecticide or other material may be introduced through the jet nozzle as subsequently more fully described.

Still further objects and advantages will become apparent from the more detailed description which follows.

In the drawings:

FIG. 1 is a longitudinal cross section of the complete main unit of a fogger adapted for operation on fuels requiring a specially heated vaporizer;

FIG. 2 is a cross section taken on the lines 2-2 of FIG. 1;

FIG. 3 is a cross section taken on the line 33 in FIG. 1;

FIG. 4 is a detail of the male portion of a quick disconnect fitting equipped with a liquid metering orifice at one end;

FIG. 4a is a sectional view of the female portion of the quick disconnect fitting adapted for installation on a flexible compression hose and further adapted to engage the male fitting of FIG. 4;

FIG. 5 is a partial cross section of the jet nozzle and air tube assembly showing its position in the outlet cone of FIG. 1;

FIG. 6 is a cross section on the line 6-6 of FIG. 5;

FIG. 7 is a diagrammatic view of the fogger unit of FIG. 1 showing the fuel, water and fog material supply and the pump operated from the engine of the vehicle upon which the fogger is mounted;

A vaporizable liquid which may be FIG. 8 shows an embodiment of the invention in which the vaporizer of the main unit of FIG. 1 has oil or other similar liquid supplied to it by a pump and in which the same pump may supply the same liquid to the burner as fuel;

FIG. 8a shows a modification of the main fogger unit of FIG. 9' or FIG. 1 in which the combustion gases are conducted upward by a right angle housing and separated from the fog jet nozzle. This modification may be specially adapted for operation with the embodiment of FIG. 8.

FIG. 9 shows a longitudinal cross section of the main unit of a fogger especially adapted for operation on LPG fuels;

FIG. 10 is a cross section on the line 10-10 of FIG. 9;

FIG. 11 is a cross section on the line 1111 of FIG. 9;

FIG. 12 is a sectional view of the intake end of the fogger of FIG. 9' drawn to a larger scale;

FIG. 13 is a sectional view toward the outlet end of the fogger of FIG. 9, also drawn to a larger scale;

FIG. 14 is a sectional plan view of the burner wheel and scale shown taken on line 1414 of FIG. 12;

FIG. 15 is a plan view of the control valve and calibrated cylinder of FIG. 12;

FIG. 16 is a cross sectional view of the air tube and jet nozzle mounted in the outlet cone of the fogger of FIG. 9 and drawn to a larger scale taken on line 1616 of FIG. 17;

FIG. 17 is a view looking into the outlet end of the outlet cone shown in FIG. 16;

FIG. 18 is a cross sectional view taken on the line 18-48 of the jet nozzle of FIG. 17;

FIG. 19 is a diagrammatic view of the main fogger unit of FIG. 9 showing the liquid propane tank, the fog material tank and the water tank. The water pump driven from a vehicle on which the fogger may be mounted is also shown, together with the connections from the fuel, water and fog material sources to the fogger.

FIG. 20 shows diagrammatically an embodiment in which the main fogger unit of FIG. 9 is operated by utilizing the pressure from the liquid propane tank to pressurize the water supply to the fogger, the connections between the propane tank, the water tank and the fogger for this operation being shown.

Referring to FIGS. 1, 2 and 3, these figures show the complete fogger except for the liquid supply system. The complete fogger unit 141 is provided with an outer casing which may be divided into three parts. The burner hous ing 12 is removably connected to the body shell 14. The nose 16 is detachably connected to the other end of the body shell 14. The body shell is supported on rear legs 18 and front leg 20 which may be spotwelded or riveted to the body shell. The body shell is tubular and may be formed by rolling a sheet of aluminized steel into a tube and spot-welding the seam. The burner housing 12 may be a similarly formed tube having a solid disc 22 seamed into its rear end. An air inlet opening 24 may be provided in the bottom of the burner housing 22. A hinged cover 26 covers an access opening 28 at the top of the burner housing. The burner housing 12 may be attached to the body shell 14 by slipping it over the outside of the latter and fastening it with self-tapping screws. The nose 16 may be attached to the body shell 14 by a flange collar 30 which overhangs an out-turned flange at the rear end of the nose. The nose is provided with an opening to permit the passage therethrough of the jet nozzle and cooling tube 32. The nose 16 is formed from a sheet of aluminized steel and is of conical form with an open front end. The joint in the nose cone is not spot-Welded but is held together by screws 34 so that the point can be opened to permit its assembly over the jet nozzle unit 32. A washer 36 is seamed or otherwise fastened into each end of the body shell 14. An inner shell 38 which may be a tube of stainless steel is carried by the Washers 36 and projects slightly beyond the washer at the rear and considerably beyond at the front so as to form an additional support for the nose 16. Thus the interior of the fogger unit forms a duct 40 having an inlet 24 and an outlet 42. Within this duct 40 a coil of steel tubing may be positioned which may constitute the main vaporizer 44. The'vaporizer 44 may be carried by three angle strips 46. These may be of stainless steel and spaced around the interior of the inner lining 38. They may be fastened to the inner lining 38 solidly at one end and by means of a screw sliding in a slot at the other end to permit thermal expansion. The rear end of the vaporizer 44 has a straight portion 45 and passes out through the burner housing end plate 22. The front end of the vaporizer coil has a straight portion 47 and is threaded for the attachment of the jet nozzle unit 32. The jet nozzle unit 32 is secured to the nose by means of the stud bolt and nut 43 which passes through a hole in the top of the nose. The'burner vaporizer 50 consists of a coil of steel tubing, one end of whichis bent backward and passes out through a hole in the rear disc 22. The other end of the burner vaporizer coil is straight and equipped with a thread which screws into the nozzle support 52. The burner nozzle 54 screws into a tapped hole in the support member 52. I The nozzle 54 has a large internal bore reduced to a small nozzle orifice 55 at the end toward the burner vaporizer 50. The size of this nozzle orifice is such as to direct a jet of vaporized fuel at high velocity through the interior of the burner vaporizer 50. hole 55 must be of the proper size to generate the desired heat and to produce an injector action which induces a flow of air into the inlet opening 24 and also into the opening 28, thence through the duct 40 and out the duct outlet 42. The burner nozzle support 52 may be secured to the end plate 22 by means of a bolt and nut 56 attached to the nozzle support 52. The rearwardly bent straight portion of the burner vaporizer coil 50 may be secured to the burner housing 12 by means of a U-clamp 58 which may be attached to the burner housing by self-tapping screws. This U-clamp 58 together with the bolt and nut 56, securely supports the burner vaporizer 50. The burner vaporizer is surrounded by a vaporizer shell 60 which extends from the forward end of the vaporizer coil rearwardly to a point roughly mid-way between the burner nozzle and the rearward burner vaporizer coil. The vaporizer shell 66 carries a vaporizer generating pan 62. This is preferably provided with a pad of glass cloth covering its bottom. This can be saturated with an appropriate fuel and ignited to generate the burner when the device is first started. If the burner fuel is used for generation, this may be supplied through the starting tube 64 which connects through the starting valve 66 with the burner control valve 68. The starting valve supplies fuel to the pan without filling the vaporizer coil 50. The burner control valve may be screwed onto a thread on the rearwardly extending end of the burner vaporizer 50. The valve 68 should meter the fuel accurately at specific angular settings. A heat insulation space 70 is provided between the lining 38 and the body shell 14. This may be filled with a heat insulation material such as vermiculite. It also may be left empty. The diameter of the turns of the main vaporizer 44 may be larger at the rear of the vaporizer to provide additional space for the burner flame without direct contact with the vaporizer coils. The angle strips 46 may be cut down in height toward the rear end to accommodate these larger vaporizer turns. The fog oil supply tube 72 is connected to the lower end of the vaporizer jet nozzle 32. This is attached to the burner housing at the rear end by a support 74. Three connecting means are provided for the liquid supply to the fogger unit 10. These may be of the quick detachable type. The male member of a fitting of this type is shown in FIG. 4. One of these male members 76 may be connected to the fog oil supply tube 72. It will be noted that the male fitting 76 is provided with a plug pierced by a small orifice nozzle 32. Different sizes of orifice 78 may be employedto meet different conditions or an adjustable orifice or valve may be used if desired. A similar male fitting 76 is also screwed on to the straight rear portion 45 of the main vaporizer 44 where it projects through the rear disc 22. In this case, the orifice 78 may be varied in a similar manner to control the liquid supply to the main vaporizer 44. The function of these orifices 78 will be more fully described. A male fitting 77, but without the plug and orifice 78,- is attached to the fuel control valve 68, which valve performs the function of the orifice 78 in regard to the fuel supplied to the burner. Fexible liquid lines may be connected to the fittings .76 and 77 by means of a quick detachable female fitting 80 shown in FIG. 4(a). By means of the fitting St the liquid lines may be quickly attached and detached to the fogger unit 10. The hinged cover 26 provides ready access for cleaning the burner nozzle 54 and may be opened for lighting the generator or for inspecting the fire. Additional air is also supplied under the right and left end of the cover 26. Reference is now made to FIGS. 5 and 6 which show the details of the vaporizer jet nozzle unit 32. The nozzle body 82 may be made of stainless steel and has an external thread on the rear and adapted to screw into the forward end 47 of the vaporizer coil 44. The other end carries an internal thread into which is screwed the expanding nozzle member 84. The nozzle orifice 86 is closely concentric with the tapered bore of the nozzle member 84 and is connected to the interior of the vaporizer 44 by an enlarged bore 88. At the bottom of the nozzle body 82 between the nozzle orifice 86 and the threaded portion of the. nozzle member 84 is an opening 90. Into this opening, a stainless steel tube 92 may be silver-soldered or welded. To the other end of this tube 92, an elbow 94 may be silver-soldered with a suitable screw connection for attachment of the tube 72. The front end of the nozzle member 84 carries serrations 96. The lower front surface of the body 82 is also provided with a slot Q8. A wire spring is urged into this slot 98 and the serrations 96 to lock the nozzle member 84 against angular movement. The liquid supply tube 92 communicates with an annular space 102 which surrounds the rear end of the nozzle member 84. The member 84 is screwed in to a point which leaves an annular aperture 104- of the proper width. Through this annular aperture which surrounds the vapor jet issuing from the nozzle aperture 86 the fog producing or treatment material is sucked in to the vapor jet by the venturi action of the jet. The annular aperture 184 should be of such width as to provide adequate vacuum and to avoid plugging. It will be seen that this construction provides an uninterrupted annular passage 104 so that an uninterrupted ring of the liquid to be atomized is exposed to the periphery of the jet. This tends to increase the quantity that can be finely atomized. The expanding bore of the member 84 extends for a short distance forwardly from the annular orifice 194. If the bore of the member 84 is made the proper amount larger than the bore 86 a fairly high vacuum can be obtained. This facilitates atomization and raising of the liquid to be atomized a considerable distance if desired, especially r' when adequate pressure is maintained in the vaporizer 44. The annular grooves 106 are for the purpose of thermally isolating the liquid in the space 102 from the hot rear portion of the nozzle body. It is desirable to keep the liquid to be vaporized reasonably cool to prevent carbonization of insecticide which might plug the nozzle and also to prevent the overheating of any insecticide or treatment material contained in the liquid to be vaporized. This purpose is also served by the jet nozzle cooling tube 108 which surrounds the forward portion of the body 82 and also the tube 92. The vapor jet issuing from the nozzle member 84 passes through an aperture 110 in the tube 188. This jet induces a flow of cool outside air into the bottom opening 112 which passes over the tube 92 and the body 82, cooling them and shielding them from the hot combustion of gases issuing from the duct outlet 42. Further, this cool air passing out the orifice 110 surrounds the jet of vapor and treatment material as it passes out the outlet 42, thus tending to shield the fog jet from the hot gas flow which surrounds it. This arrangement has been found to be advantageous when certain fogging materials are used and it permits higher gas temperatures and tends to prevent carbonization of nozzle parts. A plug 114 may be pressed into the top of the cooling tube 108. This plug may carry a bolt and nut combination 48 which connects the jet nozzle unit 32 to the nose 16. A nut 116 clamps the tube 188 to the nozzle body 82. The tube 108 is slotted on its forward side as indicated at 118 so that the assembly of the nozzle body 82, tube 92 and elbow 94 can be passed to the interior of the tube. A curved plate 120 is then attached to the front of the tube 108 to cover the slot. The plate 128 is held by the screw 122 and the inturned lip 124. The screw 126 holds one end of the spring 100 to the plate 128 which plate has a hole registering with the hole 110.

Referring now to FIG. 7, the fogger unit to previously described may be mounted on an automotive vehicle such, for instance, as a jeep or truck indicated by the number 128. Two L-shaped brackets 130 and 132 may be attached to the vehicle and the feet of the fogger unit 18 and 28 may be bolted to the horizontal member of these brackets. Due to the relative lightness of the fogger unit 18, this mounting means is adequately strong. The outlet end or front of the unit may be directed rearwardly and outwardly with relation to the vehicle so that the jet is projected in such a Way as not to eddy behind the vehicle when moving. The direction of the jet can of course be altered by varying the position of the unit 18 relative to the vehicle. For the embodiment of the invention now being described, three separate liquid sources may be employed. Two of these liquids may be supplied under pressure, one to the burner connection 76 and one to the vaporizer connection 45. As shown in FIG. 7, water or other liquid may be supplied under pressure from the pump 134 which may be a gear pump or other suitable pump driven by means of a belt 136 from the engine power take off 138 associated with the vehicle 128 and supplied with power from its power source. The water is supplied from the tank 139 to the intake of the pump 134 through the pipe 140 and shut off valve 142. The water under pressure is delivered to the vaporizer connection 45 through the pipe 144 and flexible connection 146. The pressure of the water supply may be indicated by a gauge 148. The Water pressure may be held near to the desired pressure with a spring-loaded liquid by-pass valve 150 which may be integral with the pump 134. This by-pass valve 158 has a ball valve 152 held against its seat by a compression spring, the force of which is varied by the adjustment screw 154. The spring side of this valve is connected to the pump intake and the opposite side of the valve to the pump outlet. Thus, when the outlet pressure exceeds the spring-loading of the valve, water is by-passed back to the inlet. By incorporating the by-pass valve 150 with the pump 134 and having passages of short length and large area, closer pressure regulation may be obtained. The water supply under pressure in the pipe 144 is also communicated to the fuel tank 156 through the pipe 158 and valve 160. A baffle 161 is provided where the water enters the tank 156 to prevent it from squirting upward. The fuel which may be for instance No. 1 furnace oil or kerosene is shown at 162 occupying the upper portion of the tank 156. The tank is equipped with a sight level gauge 166. Pressure is applied to the fuel 1 62 in the tank 156 by water 164 pumped into the bottom of the tank by the pump 134 through the pipe 158. As the fuel 162 is lighter than the water 164, it floats on the water and may be displaced into the flexible connection 168 which connects to the fitting 77 carried by the fuel valve 68. However, it may be desirable to supply fuel to the burner at a somewhat lower pressure than that generated by the pump in the water line 158. Thus a pressure regulating valve 170 may be employed to regulate and reduce the pressure in the line .168 below that in the line 158 and the tank 156. A gauge 172 may be employed on the outlet side of the reducing valve 170 showing this lower pressure. The regulating valve could also be installed in the line 158 and the line 168 connected directly to the tank if desired. The drain valve 174 may be opened to drain the water out of the tank 156 after it has been filled with water and all of the fuel displaced. After the tank is drained, it can then be refilled with oil through the pres sure seal filler cap 176. The level of the fuel can be seen at all times in the sight gauge 166. After the water is drained, the valve 174 is closed before the tank is refilled with fuel. The tank' 178 contains the supply of fog oil, insecticide or any formulation material 180 which may be employed. The tank 178 may be filled through an appropriate filler cap. A stand pipe 182 extends to the bottom of the tank and is connected to a valve 184 for shut off and/or adjustment of flow. This valve is connected to a strainer 186 which supplies the material 180 through the flexible connection 188 to the connection 76 and the pipe 72 which in turn connects to the pipe 92 attached to the jet nozzle body 82. It will be understood that tank 178 must be so positioned that the suction generated in the jet nozzle orifice 102 is sufiicient to raise the desired amount of the material 180. The tank may be above or below the level of the jet nozzle but must not be too far below and is generally located at or somewhere near the same level. One advantage of the lower tank is that no fog material can siphon out when operation is discontinued. The water tank 139 must also be positioned so that the pump 134 can raise the water and it may be preferable to position the water tank 139 with its bottom somewhat above the pump intake, especially when a low lift pump is employed. All three of the tanks 139, 156 and 178 may be mounted on the vehicle 128 which carries the fogger 10. If little or no portability is required the fogger may be mounted on a stand adapted to rest on the ground and the water under pressure may be supplied if desired from a municipal water faucet instead of from the tank 139 and the pump 134. If the municipal water pressure is too high or not sufficiently constant, a pressure regulator similar to the pressure regulator 170 may be connected between the municipal water faucet and the pipe 144 which may be broken at any convenient point to substitute the municipal water supply for the pump 134. FIG. 8 shows an embodiment of the invention quite similar to that of FIG. 7 except that a liquid such as No. l or No. 2 furnace oil is supplied to and vaporized in the vaporizer 44. This material may also be used for burner fuel, thus eliminating the necessity of a separate fuel tank. The common fuel and fog oil tank is given the number 132. The fuel and fog oil from the tank 139' is supplied through the pipe 148 to the pump 134' and through the flexible connection 146' to the rear end of the vaporizer 45. The fuel is supplied from the pump 134' through the reducing valve 178', the flexible line 168' to the burner fuel supply fitting 177'. The formulation material is supplied to the jet nozzle supply pipe 72' from the tank 178 through the valve 184, strainer 186' and flexible connection 188 in the same manner as described in the embodiment of FIG. 7. It may be mentioned that the orifice in the detechable connection 76 of FIG. 4 in the vaporizer connection 45 and the formulation connection 76 will most likely be of a different size than those employed in the embodiment of FIG. 7. A larger volume of fog can be produced when a fog forming material such as oil is used in the vaporizer 7 instead of water. Also the weight of the Water and tank is avoided.

Referring to FIGS. 9, 10, 11, 12 and 13, these figures show a further embodiment of the invention especially adapted for operation on fuels of the character of propane, butane, etc. known commercially as liquid petroleum gas or LPG.

FIG. 9 shows the fogger unit 309 for operation prefer ably, but not necessarily, on liquid propane. This unit is supplied with water, gas and fog oil as shown in other figures and later more fully described.

As shown in FIGS. 9, 10, I1, 12 and 13, the outer casing consists of an elongated cylinder carrying an outlet cone at one end and a burner plate at the other. The burner may be supported on the burner plate 39.2 which is connected to the body shell 304 by spacing members 306. The annular space between the burner plate 332 and the body shell 304 constitutes the air intake through which the flow of air is induced by the injector effect of the burner. The outlet cone or nose 308 is detachably clamped to the flanged outlet end of the body shell 334 by means of a bead at the large end of the nose 3% which is drawn up in clamping relation to the outturned flange by the screw clamp 310. The body shell is supported on rear legs 312 and front leg 314. The body shell 304 may be formed of a single sheet of aluminized or other suit able steel rolled into a tube with the ends welded or otherwise secured together. The nose 3ti8 may be formed into conical shape from a fiat sheet and the overlapping ends detachably secured together with screws to permit it to be assembled around the jet nozzle and air tube assembly 342 later to be described. An inner shell 316 may be a tube of stainless steel rolled up with the abutting or overlapping ends secured together, for instance by welding. Within the duct formed by the inner shell 316, a coil of steel tubing is positioned forming the vaporizer 318. Combustion gases from the burner pass mainly through the interior of the vaporizer coil. Thus, the vaporizer 318 shields the inner shell 3E6 and the inner shell shields the outer shell 304 from the heat of the burner. This reduces heat losses as well as reducing the temperature of the outer shell. The vaporizer is supported by angle fins 320 which may for instance be four in number. These fins are secured to the inner shell 316 near the outlet end by bolts 322 passing through the bent over portion of the fins 320 and through the inner shell 316 and clamped by a nut. The bottom one of these bolts 322 screws into a spacer nut 324 which together with the other bolts 322 space the inner shell 316 from the outer shell 304 near the outlet end. The spacer 324 is in turn fastened to the outer shell 304 by the bolt 326. This is the only point of fixed attachment between the outer shell 334 and the inner shell 316. Near the intake end, the inner shell 316 is spaced from the outer shell 364 by the bent over ends 328 of the fins 320. These ends are positioned by slots 330 in the intake end of the inner shell. The ends 325 are in turn prevented from inward displacement by the pieces 332 which are wider than the slots and are welded to the ends 328. The ends 328 are free to move axially in the slots 330 and also with relation to the outer shell 304 so that the parts can accommodate themselves to the expansion and contraction resulting from heating and cooling. The single attachment between the inner and outer shell by the bolt 326 also permits free expansion and contraction of the members, especially in their direction of greatest length. Supporting the inner shell on the four ends 328 also makes for easy fitting on assembly. The intake end 334 of the vaporizer 318 passesout through a hole in the burner plate 362. The outlet end of the vaporizer has a straight portion 336 which is threaded for attachment of the steam strainer 338 which encloses the strainer Screen 340. The jet nozzle unit 342 which will be later more fully described is attached in turn to the outlet end of the steam strainer 333. The jet nozzle unit 414 passes through suitable holes in the top and the bottom of the nose 308 and is attached thereto by means of the drip trough 344 which is in turn fastened to the unit 342 and to the nose 363, for instance by means of screws. The drip trough prevents liquid drip from running into the body where it might cause combustion. The burner 'tube 346 is secured to the end plate 348 which carries a mixing tube 350 which passes through the plate 348 and is threaded at the end. The mixing nozzle 352 screws on to the threaded end of the mixing tube 350 and clamps the burner unit as a whole to the burner plate 302. The other end of the mixing nozzle 352 is threaded for attachment of the burner valve 354. The burner valve unit 354 is provided with a strainer housing 356 containing a fuel strainer, not shown. It is also provided with a boss into which the pilot light valve 353 is screwed. The pilot light 366 is supplied with gas from the gas valve unit 354 by means of the connecting tube 362. Air is supplied to the pilot light through the orifice 364 which, together with the small bore gas orifice (not shown), constitutes a Bunsen-type burner. This is directed upwardly toward the burner tube 346 and made less subject to blow out by means of the U-shaped strip 366 which covers the end of pilot light 369 in closely spaced relation. in one leg of the U-member 366, a hole is provided which fits tightly over the pilot light 360 and the two parts may also be welded together or otherwise fastened. The pilot light 360 is secured to the burner plate 302 by means of a bracket 363. The gas inlet end of the burner valve 354 is provided with a male element of a quick disconnect fitting similar to that shown in FIG. 4. Fuel is supplied to this through the female portion of a quick disconnect fitting similar to that shown in FIG. 4a which in turn may be connected to a suitabie pressure hose which in turn connects to the source of propane or other fuel as will be later more fully described. The burner valve 354 includes a needle-type of valve, not shown, which is raised more or less off its seat by rotation of the burner valve wheel 374). The wheel is connected by the valve shaft to the burner scale 372 shown in plan view in FIG. 14. The figures on the scale 372 are read against the burner indicator 374 and by setting the scale so that the proper number comes opposite the indicator, a predetermined burner setting to supply the desired amount of heat may be made. After the fuel passes through the burner valve, it is discharged in a jet through the nozzle orifice 376. Primary air is induced by this jet through the air inlets 378, and mixing occurs in the mixing tube 35%. Burning and mixing with secondary air occurs in and adjacent the outer end of the burner tube 346, which also acts as a flame holder. The straight inlet end 334 of the vaporizer 318 passes out through a hole in the burner plate 302. This inlet end is threaded for a T fitting 389. In the upper opening of this T is mounted a steam pressure gauge 3t2 which indicates the steam pressure in the vaporizer 313. Into the third opening of the T 380 may be screwed the male member of a quick detachable fitting 384. This fitting is provided at its inlet end with a small orifice 386. This orifice is similar to the orifice 78 shown to a larger scale in P16. 4. The fitting 384 is also similar except that it has a male thread on the end which screws into the T 380. The end of the pressure hose 388 through which water is supplied to the vaporizer is attached to a quick connector fitting shown to a larger scale in FIG. 4a. This fitting 80 can be quickly connected to or disconnected from the fitting 384. The orifice 386 is also proportioned so as to permit the passage of the proper amount of water to maintain the desired pressure in the vaporizer as indicated by the gauge 382. This pressure may be for instance forty or fifty p.s.i., but of course a cliiferent pressure may be employed if desired. The supply of water under pressure to the hose 388 will be later more fully described. Fog oil or any desired formulation, with or without insecticide, is supplied through the hose 3% which connects to a similar quick connector fitting 392. This is detachably connected to the fitting 394 to supply the formulation to 9 the formulation control valve 396. This valve has a manually operable cylindrical scale 398 which is read against the arrow 400. The valve 396 may be a needle valve and when the cylinder 398 is turned to the right, it is fully closed and reads zero. When it is turned to the left, the needle valve is screwed up off the seat and permits the flow of formulation depending on the degree to which the valve is opened. The desired flow of formulation is secured by opening the valve to a number corresponding to the desired rate of flow. A dryer fog is produced by a smaller opening of the valve and a wetter fog when the valve is more widely opened. With maximum rate of flow large bore lines and fittings should be provided. The valve 396 is connected to a T member 402 which also receives the threaded end of the fog oil or formulation line 404. Into the third opening of the T 482 is screwed a vacuum gauge 406 which indicates the vacuum created by the flow of steam from the jet nozzle later to be described. This vacuum causes the fog oil to flow through the valve 396 and the pipe 404 to the jet nozzle. It is desirable to seal the annular passage between the outer or body shell 304 and the inner shell 316. This is done by means of the washers 408 between which is interposed a refractory sealing material 419 which may be, for instance, asbestos wicking. The washer 408 toward the inlet end is held in axial position by the bolts 322 and the washer toward the outlet end is held by the screws 412. This arrangement and also the way in which the outlet cone 398 is clamped to the body shell 304 is best shown in FIG. 13.

Referring now to FIG. 16, the outlet cone 308 carries the air tube and jet nozzle assembly generally designated as 342. The assembly 342 is secured to the tail cone 308 by means of the fitting which supports the drip trough 344 which in turn is secured to the air tube assembly by the screws 416.

Referring now to FIGS. 16, 17 and 18, the fog oil line 404 connects by means for instance of a compression fitting, not shown, to the fog oil tube 418. This tube is connected by a special fitting 420 to the riser tube 422. The fitting 423 is firmly held by a slot in the bottom of the air tube 424, the edges of which engage slots in the fitting 420. The upper end of the riser tube 422 is inserted into a hole in the jet nozzle body 426. This tube 422 may be silver soldered into the nozzle body and also into the fitting 428. The steam fitting 428 is screwed into the small threaded bore in the nozzle body 426 and clamps the nozzle body to the wall of the air tube 424. The intake end of the steam fitting 428 screws into the strainer housing 338. The multiple nozzle member 430 fits into the nozzle body 426 and forms a tight seal be tween the steam passage 432 and the fog oil passage 434. The annular passage 434 communicates with the interior of the tube 422. The nozzle outlet member 436 carries an external thread which engages a thread at the outlet end of the nozzle body 426 locking the multiple nozzle unit 430 in place. Between the members 430 and 436 is a flat conical space 438 which extends outwardly beyond the multiple steam nozzles 440 and the multiple fog oil nozzles 442. The space 438 connects to the annular fog oil passage 434 by means of a straight slot 444 in the multiple nozzle member 430. Thus a steam jet issuing from the multiple steam nozzles 440' and passing through the larger diameter fog oil nozzle holes 442 is completely surrounded by fog oil which fills the thin conical space 338. This relation has been found to give good operation. The high velocity steam jet issuing from the nozzles 44th expands, .and entrains and projects outwardly any fluid in the space 438, thus creating a vacuum and suckaxial velocity and fog oil ignition may result. If the angle is too small mixing with the hot gases is reduced and the fog may be wetter. Attention is called to the fact that the multiple fog oil nozzles 442 must be located coaxially with the multiple steam nozzles 440. This relation is insured by inserting one or more rods, the small diameter of which fits the holes 440 and the large diameter of which fits the holes 442. The member 436 is screwed up tight with these rods in place. {In fact, the torsion may be applied by means of these rods. After the retaining member 436 is tightened up, the rods may be removed and the two sets of multiple bores will then be in proper alignment. Attention is called to the ejector effect of the steam jets issuing from the fog oil nozzles 442. This ejects air from the inside of the air tube 424 which causes a fiow of air into the top and the bottom of the air tube and out through the air tube nozzle orifice 446. This flow of air prevents the hot combustion gases issuing from the outlet cone 308 from overheating the fog oil in the tube 422 and the nozzle body 426. It is especially desirable to avoid overheating of the fog oil when it carries a formulation of for instance, insecticidal material which may be decomposed and rendered relatively ineffective by excessive heat. The cool air ejected out of the orifice 446 also reduces the eifect of the hot combustion gases on the atomized or vaporized formulation issuing from the nozzles 442, the jets from these nozzles are surrounded by the hot gases issuing from the outlet cone 308, and the outward flow of the combustion gases are augmented by a second ejector effect of jets. By employing a multiple nozzle having a total area such as to produce the proper flow of steam, a longer contact line is obtained between the periphery of the steam jets and the fog oil in the space 438. This is beneficial to fine atomization. The multiple nozzle is also home ficial from the point of view of better augmentation of the flow of hot gases and reduction of aerosol particle sizes as the result of better mixing with the hot gases.

Referring now to FIG. 19, the supply of formulation or fog material to the fog oil hose 388 will now be described.

The fog oil may be contained in a fog material tank 448 having a vented filler cap 450. This tank is preferably not too high from bottom to top so as to reduce the difference in gravity head from when the tank is full to when the tank is nearly empty. The tank may be provided with a pipe 452 running to near the bottom where it may carry a strainer 454. A shut off valve 456 may be provided by means of which the flow of fog material may be cut ofl. to stop fog generation without altering the setting of the valve control valve 396. The valve 456 may be connected to the control valve 396 by means of the hose 396 and the quick disconnect fittings 392 and 394. The control valve 396 in turn connects to the fog oil pipe 404 through the T fitting 4G2 carrying the gauge 496 which shows the reduction of pressure in the fog oil line.

The fuel, which may be for instance liquid propane, may be contained in a pressure tank 458. This is provided With a shut off valve 460. This valve is connected by a pipe 462 to a pressure reducing and regulating valve 464 which, by means of a properly arranged spring-balanced diaphragm, maintains a desired pressure on the outlet side to which may be connected a fuel pressure gauge 466. This may be connected by a flexible pressure tube 468 and quick disconnect fittings 470 and 472 to the burner valve 354 from which the gas may be supplied to the nozzle orifice 376 as previously described. If liquid propane is used for fuel and if the tank 458 is sufiiciently large relative to the amount of fuel being used, sufficient vaporization will occur within the tank except at quite low atmospheric temperature. If fuels of higher boiling point are employed or use at lower temperatures intended, some form of vaporizer may be employed such, for instance, as that shown in FIG. 1 or some other type. Also by application of extra heat to the fuel tank operation may be made satisfactory at lower temperature.

Water or other liquid may be supplied to the inlet.

end 334 of the vaporizer 31.8 from a Water tank 474. This Water tank may be considerably smaller if desired than the fog material tank 448 as much less water may be used than fog oil during a given period of fogging. The water tank is provided with a vented filler cap 476. in this embodiment, the water tank may be made of light material as it is not subject to pressure. The water tank 474 is connected to a water pump 478 through a pipe 480 which may be equipped with a shut off valve 482. The pump 478 may be for instance a small gear pump and may be driven from the engine in the vehicle carrying the fogger by means of a belt 484. Other types of pump may also be employed. The pump 478 may be equipped with a spring-loaded by pass valve 486 which is interposed between the inlet and outlet and is adjusted to by pass water from the outlet to the inlet through this spring-loaded valve when the pressure exceeds a given value occasioned for instance by the speeding up of the pump drive by acceleration of the vehicle motor. The outlet of the pump 478 may be connected to a water pressure regulator 488 by a pipe 490 if closer pressure regulation is desired. The outlet side of the pressure regulator 438 carries a gauge 492 and a flexible pressure hose 388. The Water supply under the pressure determined by the setting of the pressure regulator 488 is thus main-. tained on the water supply side of the water orifice 386 in the fitting 384. Thus the Water gauge 492. shows the water pressure on the inlet side of the orifice 386 while the steam gauge 382 shows the water or steam pressure on the vaporizer side of the orifice 386. The size of this orifice and the pressure difference on opposite sides thereof determine the flow of water into the vaporizer.

By varying the size of the orifice 386 and by varying the water pressure, the fogging rate, the character and micron size of the fog-can be influenced. Also, the amount of water or other liquid consumed with relation to the amount of formulation put out in the same period of time.

Referring now to FIG. 20, there is shown an embodiment in which the fogger unit 300 and fog material tank 448 may be the same and in which the same parts are designated by the same numbers as in FIG. 19, but other parts are given higher numbers. or other liquid under pressure is supplied to the end 334 of the vaporizer 313 by the pressure of the vaporized propane supplied from the propane tank to the burner. The propane tank 494 is provided with a shut off valve 496, similar to that described in FIG. 19. A pressure regulator 498 is connected to the valve 435 by pipe 500. The pressure regulator 498 may be connected to a T fitting 502 by a connection 504 which is equipped with a pressure gauge 506. One opening of the T fitting 502 is connected to the flexible pressure hose 468 to supply fuel to the burner valve 354. The water tank 508 is constructed to withstand considerable pressure. It is provided with a pressure release or safety valve 510 which is set to release the pressure at a value considerably below that which the tank 508 can safely hold. The tank 508 may be filled with Water or other liquid to be supplied to the vaporized by means of a tightly sealing filler cap 512. A connection 514 from the tank 508 carries a shut-off valve 516. This is in turn connected to the T fitting 502 by a connecting pipe 518. Thus the pressure of the vaporized propane, or other low boiling point fuel, in the tank 494 may pass through the open valve 496, the connection 500 to the pressure regulator 498 where its pressure is reduced to for instance 50 psi. The gas then passes through the connection 504 to the T fitting 502, the pressure being indicated by the gauge 506. This pressurized gas then passes through connection 518, valve 516 and connection 514 to the tank 508 where the pressure of the gas is supplied to the Water or other suitable liquid in the tank 508. At the bottom of the tank 508 However, Water a shut off valve is provided communicating with the water in the tank. When this valve is open, water is supplied through the pressure hose 388, one end of which may be connected to the valve 529. The water in the hose 388 is supplied under the pressure indicated by the gauge 506 to the water inlet side of the orifice 386 through which it is fed to the inlet end 334 of the vaporizer 313. It will be seen that with this arrangement the same pressure will be supplied to the burner valve 354 that is supplied to the water tank 508 and to the inlet side of the water orifice 386. Both the water pressure to the vaporizer and the gas pressure to the burner may be controlled simultaneously by the pressure regulator 498. It will be seen that this constitutes a simple and effective way of supplying liquid under pressure to the vaporizer without the use of a pump. However, a heavier water tank 5% is required when the tankitself is subject to the pressure instead of the pressure appearing only at the outlet side of a pump as shown in FIG. 19. When liquid propane is employed in tank 494 and water in tank 563, there is a certain amount of absorption of the gas by the water if they are allowed to stand for extended periods of time in contact with each other under pressures substantially above atmosphere. When sufficient gas is absorbed by the water, there may be a tendency for the pressure in the vaporizer 318 to show fairly large and more or less periodic fluctuations. For this reason, it is desirable to release the gas pressure on the water tank and/or drain the water from the tank during extended periods of non-use. No additional loss of gas will result if the water tank 508 is completely filled with water through the filler 512 before operation is resumed. The gas used for pressurizing the water is only equal to the volume of water displaced at the water supply pressure and appears to be substantially less than 10% of the gas used by the burner in certain applications. This method of pressurizing the water supply makes the operation of the inger independent of any power source such, for instance, as the engine 485. The tank 508 may be provided with a water gauge 524 by which the remaining supply of water can be determined at any time. The valve 520 may also be provided with a water drain cock 526 by which water saturated with gas may be drained off. It will be understood that gas other than propane may be employed and liquid other than water may be supplied to the vaporizer 318 by pressurizing the liquid supply with pressurized gas. However, the gas and the liquid selected must be such that the gas will not be too readily soluble in the liquid. This pumpless system may be of special advantage for certain applications, for instance in a small manually portable unit, or where power to drive a pump presents difficulties.

The operation of the embodiment shown in FIGS. 9, 10, 11, 12, 13, 14, 15, 16, 17, 18 and 19 will first be described. As there is much similarity in the operation of all embodiments, it will not be necessary to describe each in complete detail. After the operation of the embodiment covered by the above-mentioned figures has been explained, the differences of operation of the other embodiments from this one will be brought out.

The fogger unit 309 may be mounted on some automotive vehicle, for instance a Jeep. The fog material tank 448, the propane or LPG tank 458 and the water tank 474 may be mounted in the body of the Jeep. The water pump 478 may be driven from the Jeep" engine 485. Other means of driving the pump 473 which requires only relatively small power may alternatively be provided. It is preferable to mount the fog material tank 448 so that its top is slightly below the horizontal center line of the fogger unit 300 so that fog material or fog oil will not siphon out when the fogger is not operating. The water tank 474 may be mounted slightly above the pump 478 so as to avoid raising the water to the pump intake. To start the fogger in operation, the valve 464} on the propane tank 458 is first opened. The pressure 13 regulator 464 is then adjusted to supply the desired pressure to the burner. The pilot light valve 358 is then opened and the pilot light 360 lit by applying a flame to the lighting hole 361. At this point the Jeep engine 485 should be in operation and driving the pump 478. The water valve 482 should be open. Water will then flow from the pressure hose 388 through the orifice 3436 into the straight intake end of the vaporizer 334 through the vaporizer 318 through the straight outlet end of the vaporizer 336 into the steam strainer 338- into the nozzle body 426 and through the multiple steam passages 440 and out the openings 442. 'After the presence of Water in the vaporizer 318 is assured, the burner valve wheel 370 is turned so that the burner scale 372 is open for instance to 8. Gas will then flow through the partially opened burner valve and issue as a jet from the mixing nozzle 376. The jet induces a flow of air into the mixing jet air openings 378 and through the mixing tube 350. This mixture of air and gas then issues from the open end of the burner shell 346 and is ignited by the flame of the pilot light 360. The gas pressure regulator valve 464 may then be adjusted so that the fuel gauge 466 reads for instance 30 p.s.i. The water pressure regulator 488 may then be adjusted so that the water gauge 492 is for instance 50 psi. A mixture of Water and steam will then issue from the openings 442. This will very shortly become dry superheated steam, if the burner valve adjustment has been properly made. The pressure in the vaporizer 318 will then approach a steady pressure for instance 40 p.s.i. as shown by the steam gauge 382.. If the setting of the burner valve is too low, the steam issuing from the openings 442 will be wet and clearly visible to the eye. The burner setting can then be slightly increased until the steam is dry and invisible. If the burner valve setting is too high, the steam gauge 3 82 will be unsteady and may show fairly large fluctuations. This can be corrected by reducing the gas supply to the burner by setting the burner dial to a lower number. When the proper setting of the burner dial is attained, the steam pressure in the vaporizer as indicated by the gauge 382 will be relatively constant. During the starting period, the fog material shut off valve 456 and/ or the fog material control valve 396 should be closed so that no fog material is delivered to the conical fog oil space 438. Under these circumstances, the vacuum created by the jets from the multiple steam nozzles 440 passing out through the fog oil openings 442 will be transmitted from the space 438 through the slot 444 through the annular passage 434 through the tube 422 through the fitting 420 and the tubes 418 and 404 to the T member 402 and will be indicated by the vacuum gauge 406. This might show for instance a vacuum of 20 inches. However, after the steam pressure in the vaporizer has been stabilized, the fog oil scale 398 may be opened for instance to eight which may give a moderate fogging rate. The shut off valve 456 may then be opened and fog oil or fog formulation will be raised from the tank 448 through the strainer 454 through the tube 452 and valve 456 to flexible tube 3%, quick disconnect fittings 392 and 394 through control valve 396 into T member 402 and thence to the fog oil space 438 by the path described for the communication between this space and the vacuum gauge. The fog oil in the space 438 surrounds each of the steam jets issuing from the multiple jet nozzles 440 and a mixture of super heated steam and fog oil vaporized and atomized to form an aerosol issues from the multiple fog oil openings 442. Cool air from the interior of the air tube 424 is also picked up by the multiple jets and passes out the opening 446 therewith. These jets in turn mix with and augment the flow of the hot gases issuing from the outlet cone 308. This flow of steam, fog oil and hot gases forms a high velocity jet which is projected axially for a considerable distance behind the outlet end of the nose 308. If it is desired to have the fog very dry, the scale 398 of the control valve 396 may be set to a lower number. The rate 14 V V at which formulation is delivered in the form of fog will then be somewhat lower. On the other hand, if it is desired to increase the rate of formulation delivery, the scale 3% is set to a higher number and may even be opened to a second or third turn depending on the construction of the valve. When the control valve 396 is opened, a large amount of formulation may be delivered per unit of time, such for instance as 30 gallons per hour. For highest delivery the bore of the whole fog oil line must be large and free of restriction. Also the fog oil lift should be minimized. Under these conditions, a wetter fog containing more large sized droplets will be delivered. A finer particle size and a dryer fog can be provided without reducing the rate of formulation delivery by setting the burner valve to a higher number to supply more heat to the vaporizer and to the hot gases issuing from the nose 348. A larger and hotter supply of steam may also be provided. However, if the burner is set too high, without increase in the water supply, fluctuations in the steam pressure may be encountered. Also, an excessively high setting of the burner valve together with a high setting of the formulation control valve 3% might cause ignition of the fog if the formulation is highly inflammable. If a fog oil such as No. 2 furnace oil is employed, more than thirty gallons per hour may be fogged with no tendency whatever to ignition of the fog oil. In fact, if the fog close to the nose 308 is ignited from the outside with a torch, it will immediately put itself out. If it is desired to briefly discontinue fogging, the shut off valve 456 may be closed, thus interrupting the delivery of fog material. During this time, the burner will still continue to operate and steam will still issue from the multiple jet nozzles. Fogging can then be resumed at any time by merely again opening the valve 456. It is desirable to place this valve within reach of an operator on the Jeep so that the fog can be turned on and oil quickly. Remote control of the valve 456 by means for instance of a flexible shaft may alternatively be provided. If it is desired to discontinue operation for a longer time, the burner valve 354 and the water valve 482 may both be closed. The pilot light 360 may continue to burn during the shut-down so that restarting is effected by simply opening the burner valve 354 and the water shut off valve 382., the burner being again relit from the pilot light. Due to the fact that the fog material supply in the tank 448 and the Water supply in the tank 474 are not subjected to pressure, the filler caps 45!) and 476 respectively can at any time be removed to determine the amount of liquid still remaining in the tanks. The supply of liquid propane in the tank 458 may be determined for instance by keeping a record of the time that the burner operates. Tanks of propane gas suitable for this purpose are available commercially and when empty may be exchanged for full tanks. Suitable equipment is also available for refilling the same tank from a private supply of liquid propane. Under the latter circumstances, any unused gas remaining in the tank reduces the amount required to refilling and there is no waste of the quantity remaining in the tank after the pressure falls below that required for operation.

The operation of the embodiment shown in FIG. 20 is similar to that described in connection with FIG. 19 and previous figures, except that no power drive or pump for the liquid supplied to the vaporizer 318 is required. To start, the valve 496 on the propane tank is opened and the pilot light 369 is lit as previously described. The valves 516 and 520 are then opened to supply water from the tank 508 through the valve 520 and the hose 588 through the vaporizer 318. The pressure regulator 498 is then adjusted until the gauge 506 reads the desired pressure, for instance 50 p.s.i. The burner valve 354 is then opened and the burner adjusted to provide the proper steady steam pressure in the vaporizer as shown by the steam gauge 382 as has been previously described. The gauge 566 may show a pressure of for instance 50 psi. which will be, in this embodiment, the pressure applied to the burner and also to the water supply in the tank 563. The operation of this embodiment is otherwise substantially the same as that described in connection with FIG. 19. To terminate operation, the valve 496 may be closed. The valve 516 and the valve 526 may then also be closed to completely shut down the fogger. If operation is resumed again shortly, for instance within an hour or so, and if the water supply as indicated by the water gauge 524 has not been exhausted, operation of the fogger can be resumed by following the same procedure as described when first starting. However, if operation is not to be resumed until the next day or a longer period, it is desirable to release the gas in the tank 598 to prevent too much absorption of gas by the water. This pressure may be released for instance by partially opening the filler cap 512 until the pressure has fallen to atmosphere. This should be done out of doors where released gas is immediately dissipated. The tank 503 may then be completely filled with water and the filler cap replaced. It is then ready for a new start. This procedure prevents the absorption of the gas in the tank 568 by the water which may interfere with the best operation if gas under pressure stands for long periods in contact with the water. If the water in the tank 508 has already absorbed too much gas, the water may be drained from the tank by means of the drain cock 526 and the tank completely refilled with fresh water. No inflammable mixtures can be formed within the gmk 508 as long as it is kept full of either propane gas or water. Propane gas mixtures with air in order to be inflammable must contain nearly 90% of air. This condition could never be present with proper operation and, even if it were, a flame or spark would still have to be applied to the interior of the tank. Like a gasoline tank, a propane tank should not stand with its cover removed in the presence of fire. The special features of the operation of the embodiment of FIGS. 1, 2, 3, 5, 6 and 7 will now be described. The fogger shown in these figures is similar to the embodiment shown in FIG. 9 except that the fogger in FIG. 1 is adapted to operate with fuel such as kerosene or furnace oil which requires a source of heat other than atmospheric temperature for satisfactory vaporization.

It may be mentioned that when LPG consisting mainly of butane or other higher boiling point materials is used, a vaporizer heated by other means besides atmospheric temperature may be required. This may even be true of propane at low atmospheric temperatures when a large amount of fuel is being used from a relatively small fuel tank. It should be noted that the kind of vaporization employed depends on the particular fuel used and the prevailing atmospheric temperature. ,When the heat of the burner flame is used to vaporize the burner fuel, the surface of the vaporizer and the proximity to the flame may be different for such difierent conditions. A vaporizer remote from the burner may be employed either heated indirectly from burner heat supply or from an entirely separate heat source other than the atmosphere. Other differences between the embodiment of FIG. 1 and :FIG. 9 will be apparent from the descriptions.

Referring particularly :to FIG. 1 and FIG. 7, this fogger is started as follows. The fog material valve 184 should be closed. When the pump 134 has been started and the water valve 142 has been opened, water under pressure will be supplied to the fuel tank @156 through the outlet connections 1 44, 158, and valve 160 which should be open. The water pressure is indicated by the gauge 148 and may for instance be in the vicinity of 60 psi. This approximate pressure is maintained by the proper adjustment of the pump by-pass valve 152. This pressure is also exerted on the fuel 162 in the tank 156. The priming valve 66 is then opened and fuel flows through the pressure regulator 170 which may be set to maintain a presure of for instance 40 psi. as indicated 15 by the gauge 172. Fuel will then flow into the generating pan 62. This fuel is then lit from an external flame and burns heating the vaporizer coil 50. When this is sufficiently hot, which may be in a matter of three to five minutes, the burner may be turned on. It may be mentioned that during generation of the burner, the cover 26 may be open. Operation of the pump 134 also supplies water at the pressure indicated by gauge 148 to the vaporizer 45. A quick connector fitting similar to that shown in FIG. 4 is mounted on the end of the vaporizer 45. This is provided with an orifice similar to the orifice 78 but generally somewhat smaller which controls the water supply to the vaporizer. The amount of water passing through this orifice is determined by the size of the orifice and the pressure differs on opposite sides thereof. The water flows through the vaporizer 45 through the outlet ends 44 and 47 through the steam orifice 86 and out the hollow threaded member 8'4. The burner valve 68 is now opened slightly and the burner starts. After the vaporizer 50 has been additionally heated by the burner flame, the burner valve 68 is opened to the proper operating burner setting which may be for instance 3 /2. It should be mentioned that the priming valve 66 may be closed except for maintaining the priming fire during burner generation. The burner flame during prefer-red operation may be bluish-yellow and does not extend substantially further toward the outlet than the larger diameter turns of the vaporizer. It is desirable that combustionshould be completed toward the inlet and of the combustion duct formed by the inner lining 38. The burner is adjusted to maintain the desired steam pressure in a manner similar to that described in connection with the embodiment of FIGS. 9 and 19 and a similar steam gauge may be provided for this purpose. The proper burner operation can also be determined by adjusting the temperature to keep the issuing steam jet dry and to provide a fairly uniform pressure in the vaporizer. if pressure fluctuations occur, these can be detected by the sound. However, a steam gauge is desirable. The water pressure as shown by the gauge 148 can be kept reasonably constant by means of a properly constructed and regulated by-pass valve 152. However, better pressure control can be obtained with an additional pressure regulator which may be inserted in the connection 146. A single pressure regulator in the line 144 may also be employed to regulate both the water and fuel pressure. However, this would require the use of the same pressure on the water supply to the vaporizer and the fuel supply to the burner. It has been found that under certain conditions a lower pressure on the fuel to the burner is desirable. When a uniform flow of dry, preferably superheated, steam has been established from the opening in the threaded member 84, the fog oil or formulation valve 184 may be opened. Steam passing through the steam orifice 86 expands, entrains fluid in the space 104 and forms a vacuum in this space which is communicated to the annular space 102 to the interior of the tube 92 to the interior of the tube '94 through the tube 72 and the quick disconnect fittings 76, the flexible connection 188, the strainer 186, the valve 134 and the pipe 182 projecting close to the bottom of the fog material tank 178. When the valve is closed, a vacuum is produced within these passages which may be from 18 to 24 inches or thereabouts. A vacuum of 20 inches is satisfactory under certain circumstances of operation which have been carried out. 'When the valve 184 is opened, fog oil is drawn from the tank 178 by the path previously described to the annular clearance space 104. Here it is picked up by the issuing steam jet finely atomized and discharged as a thermal aerosol out the opening in the threaded member 84. In passing through the round opening in the air tube cover 120, air from the inside of the air tube is entrained, thus creating a flow of air into the air tube opening 112 and out the opening 110. The jet issuing from the outlet opening 42 of the nose or outlet cone 16 also augments the flow of combustion gases and air established by the burner in the duct within the inner lining 14. The air tube prevents overheating of the formulation in the nozzle body 82 and the tube 92 and functions in a way similar to that described in connection with the operation of the embodiment of FIG. 9. It will be noted that the nozzle and air tube assembly 32 is located further back from the outlet end of the outlet cone 16 than the corresponding parts shown in FIG. 9'. The location of the jet nozzle further from or closer to the outlet of the cone 16 may considerably influence the operation. For instance, more heating of the fog oil by the hot combustion gases occurs with the jet nozzle further from the outlet. However, if the temperature of the combustion gases is high and a rate of inflammable fog oil delivery is employed, there is a possibility of fog oil ignition. This tendency appears to be reduced at least under some circumstances by positioning the jet nozzle closer to the nose outlet as shown in FIG. 9 and FIG. 16.

Referring now to FIG. 8, this shows a diagrammatic view of an embodiment of the invention in which similar numbers indicate the corresponding parts except that a prime has been added to the numbers. The fogger of this embodiment may be the same as shown in FIG. 1 and the fog material tank line and nozzle may be the same as in the previous embodiment. However, the tank 139' may contain for instance No. 2 furnace oil, No. 1 furnace oil, or a mixture of the two. The contents of this tank constitutes fuel for the burner as well as the liquid supplied to the vaporizer through the connecting member 146'. The No. 1 oil is better for the burner, but does not form as dense a fog as No. 2 oil. The burner, however, will operate although with a yellower flame on the No. 2 oil. The pump 134 may be operated in the same manner described in the previous embodiment or by other means. The starting, adjusting and operating are similar to that previously described. However, a dilferent burner setting may be required and a different diameter of orifice to determine the amount of oil delivered to the vaporizer 45. If the fog material does not contain, for instance, dissolved insecticide sensitive to heat, the fog material tank and feed line may be completely dispensed with and the fog produced entirely by the jet of vaporized oil or other fog-forming fluid issuing from the steam orifice 82. This arrangement would be especially suitable for producing obscuring fogs for military purposes or fog to prevent freezing for instance in orchards. However, where a heat sensitive insecticide or other material is to be distributed by the fog, its passage through the vaporizer can be avoided by providing a fog material containing a high percentage of insecticide in the tank 178' which passes through the valve 184', the strainer 186, the line 188, the tube 72', the tube 92, the annular passage 102 and the annular clearance 104, and is sucked in and entrained by the oil vapor jet from the orifice 82. In this form of operation, the insecticide is all contained in the fog material in tank 178 and is mixed with the pure oil vapor from the tank 139' in the opening in the threaded member 84 and in the jet beyond. With this form of operation the vaporized oil issuing from the orifice 82 dilutes and enhances distribution of the insecticide and may persist longer in the atmosphere and carry greater distances than when water is employed. The use of water or oil in the vaporizer to produce the atomizing jet each have their particular advantages. The use of oil supplied to the vaporizer to produce the atomizing jet may also be employed in the embodiment of FIG. 20 in which case an appropriate oil would be substituted for the water in the tank 508. When an inflammable oil such as No. 2 furnace oil is used in the vaporizer to create the fog jet, there is more likelihood of ignition of the fog at the fog outlet 42 than when water is employed in the vaporizer. This tendency can be reduced by controlling the temperature, the position of the jet nozzle with respect to the fog outlet, and by other means. Also, this difficulty can be completely eliminated by employing the type of fog outlet and jet nozzle shown in the modification of FIG. 8a. The outlet end of the fogger 10 is provided with an upturn combustion gas outlet housing 600. The hot combustion gases pass in a horizontal direction from the duct formed by the inner lining 38 into the housing 600 and are discharged upwardly from the open top 602 of this housing. The end 47 of the vaporizer 44 projects through a hole 604 in the housing 600. The jet nozzle 606 may be similar to that shown at 82, 84, etc. in FIG. 5 or to that indicated by the numbers 426, 430, 436, etc. in FIGS. 16, 17 and 18 except that the air tube 424 is here unnecessary because the combustion gases are deflected upward and do not pass over the nozzle 606. This nozzle is located at a suflicient distance from the hot gas outlet 602 so that no ignition of the jet from the nozzle 606 can be produced by the hot exhaust gases issuing from outlet 602. The fog oil or formulation is supplied through the tube 72 and 92 to the annular clearance space 104 for instance as shown in FIG. 5. Although the arrangement of FIG. 8a is advantageous for the purpose of preventing fog light up, especially when the fog jet is produced by oil supplied to the vaporizer, it does not provide certain of the advantages which are obtained by mounting the jet nozzle in the outlet cone as shown in other figures, such as FIGS. 5 and 16. One of these advantages is the use of the hot flue gases for additional vaporization of the fog oil. The heat contained in these gases are wasted in the embodiment shown in FIG. 80. Another advantage which this embodiment sacrifices is the injector effect of the jet issuing from the jet nozzle in augmenting the flow of hot gases initiated by the burner through the duct around the jet and out the fog outlet. This effect is quite advantageous for stabilizing the operation of the burner. With the jet outlet arrangement shown in FIG. 5 or FIG. 16 the action of the burner is almost entirely independent of external wind conditions due to the augmented flow of the hot gases produced by the jet. With the upturned outlet of FIG. 8a, operation in a high wind or at a high vehicle speed may be somewhat erratic. Further, if oil is used instead of water in the vaporizer, the oil is still consumed and fogging cannot be stopped by closing the fog material valve 456. However, if propane is employed as burner fuel as in FIG. 19 or FIG. 20 when oil is supplied to the vaporizer 318 or 45, then fog may be shut off by closing the burner valve 354 to put out the fire and then closing the valve 142 to stop oil supply to the vaporizer. Pegging is resumed by reopening the burner valve 354 whereupon the pilot light 360 relights the fire. The valve 142 is then also opened. On the other hand, the burner of FIG. 1 and FIG. 8 requires generation to relight except for brief fire stoppage. It will thus be seen that the embodiment shown in FIG. 8a may be more or less advantageous, depending on the particular use and type of operation desired.

Referring again to the operation of the fogger on propane or LPG asillustrated in the embodiments of FIGS. 19 and 20, it should be noted that LPG is a cheap and advantageous fuel which is quite widely available in the United States. In some areas, LPG is substantially cheaper than gasoline or even diesel fuel. It is also advantageous in that it may not require heating of a vaporizer prior to lighting of the burner. The burner may also be turned on and off at will and will relight from the pilot light. The pressure under which propane for instance is stored is also suificient to deliver the fuel to the burner and also water to the vaporizer, thus eliminating pumps and the power required to operate them. However, LPG fuels must be stored in pressure-resistant containers. These are more expensive than a kerosene or fuel oil tank. Also, kerosene and fuel oil are more widely obtainable than LPG. In fact, in many places in the world where 'foggers are used LPG is not obtainable at all or would be prohibitively expensive. It will thus be seen that the embodiment of FIG. 1 may be required in some circumstances while the embodiment of FIG. 9 is advantageous in others.

I claim:

1. In a fogging apparatus a liquid fuel source, a combustion duct having an air inlet and a hot gas outlet, a burner having a jet nozzle connected to said liquid fuel source discharging liquid fuel under pressure in a high velocity jet into one end of said duct where combustion is completed and a flow of heated gases is produced, a water tube boiler in heat-absorbing relation with the heated gas in said duct, means forcing water into one end of said boiler, a second high velocity jet of steam issuing from nozzle means at the other end of said boiler and directed out said hot gas outlet so as to mix with and accelerate said hot gases, means associated with said nozzle means communicating with a source of fog-forming materials whereby said fog-forming material is sucked in and entrained by said jet so that the stoppage of the steam jet simultaneously stops the flow of fog material and means between the fog material source and the nozzle means for stopping and starting the flow of fog material while the transparent jet of steam and combustion gases continues uninterrupted fiow.

2. In an apparatus for producing a thermal aerosol comprising a hot gas duct having a hot gas outlet therein, a vapor jet injector burner in said duct, a source of liquid fuel, means supplying vaporized liquid fuel from said source under pressure to said burner, said burner being supplied with air at substantially atmospheric pressure from an air intake in said duct by its own injector action, a boiler in said duct, a jet nozzle connected to the outlet end of said boiler discharging a jet of vaporized liquid into the atmosphere adjacent the outlet end of said duct, said boiler being disposed between said burner and said outlet, a source of vaporizable liquid under pressure supplying liquid to said boiler against the pressure therein whereby the gas flow through the duct and over the boiler is produced by the injector effect of the vapor jet injector burner without mechanical power except such small amount as may be employed for boiler feed.

3. In an apparatus for producing a thermal aerosol without employing appreciable mechanical power, a hot gas duct having an air intake communicating with the atmosphere, a burner in said duct supplied with air from said air intake by its own injector action, an outlet opening to the atmosphere in said duct, a boiler in said duct between said burner and said outlet, a jet nozzle connected to said boiler, a ource of fluid under pressure supplying fluid to said boiler against the pressure therein, a source of aerosol liquid connected to said nozzle, said nozzle being constructed and arranged to suck in aerosol liquid and to discharge it together with pressurized fluid into the atmosphere as a thermal aerosol jet.

4. In an apparatus for producing a thermal aerosol comprising a hot gas duct having a hot gas and aerosol outlet opening therein, a burner in said duct, a. boiler in said duct between said burner and said outlet, an ejector nozzle connected to said boiler and positioned inside said duct between said boiler and said outlet opening, said nozzle, duct and opening constituting an ejector creating a large flow of air andcombustion gases through said duct and out said opening, an air intake in said duct through which air is supplied at substantially atmospheric pressure by the reduced pressure in said duct established by said ejector, a source of fluid under pressure supplying fluid to said boiler against the pressure therein, a source of aerosol material connected to said nozzle, said nozzle being constructed and arranged to suck in aerosol material and discharge it together with the ejector fluid and combustion gases from said outlet opening, the gas flow being produced by mean of the burner heat applied to the boiler and without substantial mechanical power except such small amount as may be used for boiler feed.

5. A fogger including a hot gas duct having an inlet and outlet, burner means, a fuel supply thereto, said burner means being adapted to establish a flow of burning fuel and air in said duct and to expel hot combustion gases from said duct outlet, a source of vaporizable fogforming liquid, a boiler in said duct between said burner and said duct outlet, means for forcing vaporizable fogforming liquid from said source into said boiler against the pressure of the vaporized liquid therein, a jet nozzle supplied with hot pressurized fog-forming vapor from said boiler, said jet nozzle directing a diverging jet of fogforming vapor toward the duct outlet to mix with and speed up the flow of the combustion gases, whereby a jet of fog is projected into the atmosphere without substantial mechanical power except such small amount as may be used for boiler feed.

6. Fog generating apparatus comprising a hot gas duct, means causing a flow of hot gases through said duct, a burner in said duct, a pressure-resistant fuel tank, a connection from the top of said fuel tank to said burner through which fuel is supplied thereto, a pressurized source of a liquid heavier than the fuel, a boiler in said duct heated by said burner, a jet nozzle connected to said boiler from which a jet of the vapor of the heavier liquid issues, a connection between said pressurized source of heavy liquid and the lower part of said fuel tank through which the heavier liquid enters and pressurizes said fuel tank to supply fuel to said burner and means associated with said fuel tank for draining the heavier liquid therefrom after the fuel has been displaced by said heavier liquid and then again refilling said fuel tank with the lighter fuel.

7. In an apparatus for producing a thermal aerosol comprising a hot gas duct having a hot gas outlet therein, a vapor jet injector burner in said duct, means supplying vaporized combustible liquid under pressure as a high speed jet to said burner, said burner being supplied with air at substantially atmospheric pressure from an air intake in said duct by its own injector action, a boiler in said duct, a jet nozzle connected to said boiler discharging a jet of vaporized combustible liquid as a thermal aerosol into the atmosphere adjacent the outlet end of said duct, said boiler being disposed between said burner and said outlet, and means supplying combustible vaporizable liquid under pressure to said boiler against the pressure therein, the gas flow through the duct and over the boiler being produced by the injector efiect of the vapor jet injector burner without substantial mechanical power.

8. A fog generator including a hot gas duct having a burner air inlet and a combustion gas outlet, a burner, a source of combustible vaporizable fog-forming liquid, means supplying said vaporized liquid from said source under pressure to said burner as fuel, means mounting said burner within the burner end of said duct, a boiler in said duct between said burner and said combustion gas outlet, means for forcing said vaporizable liquid from said source into, said :boiler against the pressure of the vaporized liquid therein, jet nozzle means connected to the outlet of said boiler discharging said vaporized liquid from said boiler as a high velocity jet of fog into the atmosphere adjacent the outlet end of said duct.

9. The method of producing vapor under pressure without mechanical power, comprising the steps of con fining a liquid fuel at a temperature above its boiling point, releasing the vaporized fuel under pressure as a high speed jet so as to inject air together with the vaporized fuel into a combustion area adjacent one end of a confined space where the fuel-air mixture burns and flows over said confined space and thence into the atmosphere, employing the pressure of said fuel vapor to force a vaporizable liquid into said confined space in heatexchange relation with the combustion gases, releasing the vapor. generated by the heat of the combustion gases from an orifice in said confined space remote from said com;

21 bustion area as a jet of fog-forming vapor into the atmosphere.

10. The method of producing a hot mixed fog jet without requiring mechanical power, comprising the steps of, providing a liquid fuel confined at a temperature above its boiling point, releasing the vaporized fuel under pressure as a high speed jet into a combustion space, burning the fuel air mixture to establish a flow of hot combustion gas, passing the combustiongas into heat exchange relation with a confined vaporizable liquid, employing the pressure of said fuel vapor to pressurize said confined vaporizable liquid and to force said liquid into said heat exchange relation, causing the vapor of said liquid vaporized by the heat of said combustion gases to issue as a jet into said combustion gas and then causing the combined jet of vapor and combustion gas to issue into the atmosphere as a fog.

11. In an apparatus for generating a jet of hot mixed fluid without mechanical power, a pressure tank containing a liquid fuel boiling substantially below ambient atmospheric temperature, a second pressure tank containing a vaporizable liquid, a hot gas duct, having an outlet to the atmosphere adjacent one end, a boiler in said duct, a burner for heating said boiler by establishing a flow of hot combustion gases through said duct, connecting means supplying vaporized fuel from said fuel tank to said burner, connecting means supplying vaporized fuel from said fuel tank to said vaporizable liquid tank, means connecting said vaporizable liquid tank below the liquid level of said tank to said boiler to force said liquid into said boiler by means of the vapor pressure from said fuel tank, nozzle means connected to said boiler through which vapor from said vaporizable liquid issues in a jet mixing with and ejecting the combustion gases as a hot mixed fluid jet from the outlet end of said duct.

12. Fog generating apparatus comprising a duct, means causing a flow of hot gases through and out the outlet end of said duct, a jet nozzle having a jet fluid inlet and a fog material inlet discharging into said duct, a source of jet fluid under pressure, a source of fog material, means connecting said fluid source to said jet fluid inlet, means connecting said fog material source to said fog material inlet, an entrainment chamber connected to said fog material inlet, a jet fluid bore from said jet fluid inlet into one side of said entrainment chamber, a removable member forming one side of said entrainment chamber, a bore in said removable member in alignment with said jet fluid bore, said outlet bore being larger than said jet fluid bore and adapted to project an expanding jet of fluid and finely divided, entrained fog material toward and out the outlet end of said duct together with said hot gases.

13. In apparatus for generating a thermal aerosol jet, a duct discharging hot gases, a cooling jacket projecting into said hot gases having a cool air inlet outside said duct, jet nozzle means inside said cooling jacket, means inside said duct supplying pressurized jet fluid under pressure to said jet nozzle means, means passing through said cooling jacket supplying aerosol material to said jet nozzle means and an outlet opening in said cooling jacket positioned in relation to said jet nozzle means and said duct so that the jet fluid projected from said jet nozzle means first entrains aerosol material from said nozzle means, then cooling air from said cooling jacket and finally hot gases from said duct to eject a thermal aerosol jet.

l4. Fog generating apparatus comprising a hot gas duct, a burner discharging hot gases into one end of said duct, a source of jet fluid under pressure, a source of fog material, a jet nozzle having a jet fluid inlet and a fog material inlet positioned within said hot gas duct to augment the flow of burner gas out the other end of said duct to the atmosphere, tubular means for heat transfer from said hot gases to said jet fluid within said duct connecting said fluid source to said jet fluid inlet, means connecting said fog material source to said fog material inlet, an entrainment chamber connected to said fog material inlet, a fluid jet passage from said fluid inlet into said entrainment chamber, jet outlet means from said entrainment chamber adapted to project an expanding volume of jet fluid and finely divided entrained fog material mixing with and being heated by the hot gases in said duct and discharging a finely divided aerosol fog into the atmosphere.

15. The method of producing a jet of hot mixed fogforming fluids comprising the steps of, providing a liquid fuel under pressure at a temperature above its boiling point, releasing the fuel vapor as a high velocity jet so as to entrain air and establish a flow of air and fuel into a combustion space by the injector effect of said jet, burning the mixture in said combustion space at substantially atmospheric pressure, applying pressure to a vaporizable fog-forming liquid, causing said liquid to flow into confined heat exchange relation with said combustion gases, effecting the vaporization of said vaporizable fogforming liquid by the heat of said combustion gases, releasing the resulting vapor as a second high velocity jet into said combustion gases and heated air so as to speed up the gas flow through said combustion space and to expel a blast of combined combustion gases, air and vaporizable fog-forming liquid into the atmosphere by the ejector action of said second jet.

'16. The method of producing a hot mixed gas and vapor jet comprising the steps of filling a pressure resistant fuel space with liquid fuel, pressurizing a heavier vaporizable liquid, causing said pressurized liquid to enter said fuel space to displace said lighter fuel, burning said displaced fuel in a combustion space, applying heat from said burning fuel to a pressure resistant vapor generating zone within said combustion space, utilizing the pressure of said heavy liquid to force it into said vapor generating zone against the vapor pressure therein, pass ing said hot vapor out of an outlet in said vapor generating zone as a vapor jet into said combustion space and causing said vapor jet to issue from said combustion space'together with combustion gases as a mixed gas and vapor jet.

17. In an apparatus for generating a jet of hot fog without mechanical power, a pressure tank containing a liquid fuel boiling substantially below ambient atmospheric temperature, a second pressure tank containing a vaporizable fog-forming liquid, at hot gas duct, a boiler in said duct, a burner for heating said boiler by establishing a flow of hot combustion gases through said duct, connecting means supplying vaporized fuel from said fuel tank to said burner, connecting means supplying vaporized fuel from said fuel tank to said vaporizable fogforming liquid tank, means connecting said vaporizable fog-forming liquid tank below the liquid level of said tank to said boiler to force said liquid into said boiler by means of the vapor pressure from said fuel tank, nozzle means connected to said boiler through which vapor from said vaporizable fog-forming liquid issues as a fog jet to the atmosphere in a generally horizontal direction, means for causing the hot combustion gases to issue from said duct after passing over said boiler.

18. In a portable apparatus for generating a jet of thermal aerosol, a duct having an air inlet and a hot gas outlet, a burner in said duct, a boiler in said duct between said burner and said outlet, a pressure tank containing a liquid fuel boiling substantially below ambient atmospheric temperature, connecting means supplying vaporized fuel from said fuel tank to said burner as a high velocity jet, said jet establishing a flow of hot cornbustion gases in said duct over said boiler and to the atmosphere through said hot gas outlet, a second tank containing a vaporizable liquid, means connecting said second tank below the liquid level of said tank to said boiler to supply vaporizable liquid to said boiler against the vapor pressure therein, means connected to said fuel tank adapted to force vaporizable liquid from said second tank into said boiler by the pressure of the vaporized fuel, and nozzle means connected to said boiler through which said vaporizable liquid issues to the atmosphere as a thermal aerosol in a generally horizontal direction.

19. Fog generating apparatus comprising a duct, means causing a flow of hot gases through and out the outlet end of said duct, a jet nozzle in said duct having a jet fluid inlet and a fog material inlet discharging jet fluid and fog material toward the outlet end of said duct, a source of jet fluid under pressure, a source of fog material, means connecting said jet fluid source to said jet fluid inlet, means connecting said fog material source to said fog material inlet, a plurality of jet fluid bores diverging from each other as they pass from the jet fluid inlet to an entrainment chamber connected to said fog material inlet, an outlet bore in the opposite wall of said entrainment chamber in alignment with each of said jet fluid bores, said outlet bores being larger than said jet fiuid bores and adapted to project diverging jets of jet fluid and finely divided entrained fog material toward and out the outlet end of said duct together with said hot gases.

20. A fog generating apparatus including a hot gas duct having an air inlet and a hot gas outlet, a burner in said duct, a boiler in said duct between said burner and said outlet heated by said burner, a tank of vaporizable liquid, a power-driven pressure pump supplied with liquid from said tank, connecting means supplying liquid from said pump to the liquid intake of said boiler, automatic means operatively associated with said pump adapted to maintain a uniform flow of vaporizable liquid into said boiler, a jet nozzle connected to the vapor outlet of said boiler, fog material entrainment means in said nozzle from which fog material is entrained by said vapor jet, a fog material tank, means supplying fog material from said tank to said entrainment means, means mounting said fog generating apparatus, said vaporizable liquid tank, said fog material tank and said pump on a vehicle propelled by an engine, means for driving said pump by power derived from said vehicle engine, said fog generating apparatus projecting fog behind said vehicle consisting of entrained fog material and vapor from said jet nozzle substantially without mechanical power except that derived from the engine of said vehicle.

21. A fog generating apparatus including a hot gas duct having an air inlet and a hot gas outlet, a burner adjacent one end of said duct, a boiler in said duct between said burner and said outlet heated by said burner, a tank of vaporizable liquid, a pressure pump supplied with liquid from said tank, means connecting the pressure side of said pump to the liquid intake of said boiler to replace liquid vaporized therein, a nozzle connected to the vapor outlet of said boiler, a tank of fog-forming material, a fog material passage supplying fog-forming material from said tank to entraining means in said nozzle, said nozzle projecting a jet of combined vapor from said boiler and entrained fog material from said fogforming material tank into the atmosphere.

22. In a portable apparatus for generating a jet of hot fog without mechanical power, a pressure tank containing a liquid boiling substantially below ambient temperature, a second pressure tank containing a vaporizable fogforming liquid, an elongatedgenerally tubular housing, a boiler in said housing, a burner adjacent one end of said housing for heating said boiler, combustion air supply means in said housing adjacent said burner, an upwardly directed outlet means for said combustion gases after passage over said boiler, connecting means supplying vaporized fuel from said fuel tank to a high velocity jet in said burner adapted to entrain air and create a flow of hot gas through said housing over said boiler and out said upwardly directed outlet means, connecting means supplying vaporized fuel from said fuel tank to said vaporizable liquid tank establishing a substantial pressure therein, means connecting said vaproizable liquid tank below the liquid level in said tank to said boiler to force said vaporizable liquid into said boiler by means of the vapor pressure from said fuel tank, a metering orifice in said connecting means to limit the flow of vaporizable liquid to said boiler to a predetermined rate, ,a jet outlet from said boiler passing through the wall of said housing opposite the burner end and projecting a jet of fog in a direction generally corresponding to the major axis of said housing so that said fog jet may conveniently be projected horizontally.

23. The method of producing a thermal aerosol comprising the steps of confining a liquid fuel, subjecting it to a temperature above its boiling point, thus producing a vapor substantially above atmospheric pressure, releasing the vapor through an orifice to form a high velocity jet of vaporized fuel, inducing a flow of air into a combustion space by directing said jet of vaporized fuel into said combustion space, burning the injected fuel-air mixture at substantially atmospheric pressure in said combustion space to produce a flow of air and hot gases therethrough, forcing a vaporizable liquid into a confined liquid space within said combustion space without mechanical power except such small amount as may be employed for feeding said vaporizable liquid, vaporizing said vaporizable liquid to produce a vapor substantially above atmospheric pressure by the heat of said flow of combustion gases in heat-exchange relation over said confined liquid space, releasing said liquid after vaporization from an orifice in said confined liquid space to form a second jet.

References Cited in the file of this patent UNITED STATES PATENTS 1,058,850 Deemar Apr. 15, 1913 1,454,975 Martindell May 15, 1923 1,825,131 Shepherd Sept. 29, 1931 1,992,851 Adams Feb. 26, 1936 2,192,996 Fenzl 'Mar. '12, 1940 2,378,184 Carlson June 12, 1945 2,391,422 Jackson Dec. 25, 1945 2,418,098 Rutf Mar. 25, 1947 2,451,019 Davis Oct. 12, 1948 2,565,543 Arvintz et a1 Aug. 28, 1951 2,599,465 Letvin et al. June 3, 1952 2,607,743 vHession Aug. 19, 1952 2,630,412 Besler Mar. 3, 1953 2,667,459 Besler Jan. 26, 1954 2,821,986 Tenney Feb. 4, 1958 2,836,567 'Reure et al. May 27, 1958 2,889,284 Haynes et a1 June 2, 1959 FOREIGN PATENTS 851,159 France Sept. 25, 1939 

10. THE METHOD OF PRODUCING A HOT MIXED FOG JET WITHOUT REQUIRING MECHANICAL POWER, COMPRISING THE STEPS OF, PROVIDING A LIQUID FUEL CONFINED AT A TEMPERATURE ABOVE ITS BOILING POINT, RELEASING THE VAPORIZED FUEL UNDER PRESSURE AS A HIGH SPEED JET INTO A COMBUSTION SPACE, BURNING THE FUEL AIR MIXTURE TO ESTABLISH A FLOW OF HOT COMBUSTION GAS, PASSING THE COMBUSTION GAS INTO HEAT EXCHANGE RELATION WITH A CONFINED VAPORIZABLE LIQUID, EMPLOYING THE PRESSURE OF SAID FUEL VAPOR TO PRESSURIZE SAID CONFINED VAPORIZABLE LIQUID AND TO FORCE SAID LIQUID INTO SAID HEAT EXCHANGE RELATION, CAUSING THE VAPOR OF SAID LIQUID VAPORIZED BY THE HEAT OF SAID COMBUSTION GASES TO ISSUE AS A JET INTO SAID COMBUSTION GAS AND THEN CAUSING THE COMBINED JET OF VAPOR AND COMBUSTION GAS TO ISSUE INTO THE ATMOSPHERE AS FOG. 